A pharmaceutical composition is a formulation which contains at least one active ingredient (such as a Clostridial toxin) as well as, for example, one or more excipients, buffers, carriers, stabilizers, preservatives and/or bulking agents, and is suitable for administration to a patient to achieve a desired diagnostic result or therapeutic effect. The pharmaceutical compositions disclosed herein have diagnostic, therapeutic and/or research utility.
For storage stability and convenience of handling, a pharmaceutical composition can be formulated as a lyophilized (i.e. freeze dried) or vacuum dried powder which can be reconstituted with a suitable fluid, such as saline or water, prior to administration to a patient. Alternately, the pharmaceutical composition can be formulated as an aqueous solution or suspension. A pharmaceutical composition can contain a proteinaceous active ingredient. Unfortunately, a protein active ingredient can be very difficult to stabilize (i.e. maintained in a state where loss of biological activity is minimized), thereby resulting in a loss of protein and/or loss of protein activity during the formulation, reconstitution (if required) and storage of the pharmaceutical composition prior to use. Stability problems can arise due to surface adsorption of a protein active ingredient, physical instability, such as, e.g., denaturation or aggregation, or chemical instability, such as, e.g., cross-linking, deamidation, isomerization, oxidation, formation of acidic or basic species, Maillard reaction, and fragmentation. To prevent such instability, various protein-based excipients, such as albumin and gelatin, have been used to stabilize a protein active ingredient present in a pharmaceutical composition.
Unfortunately, despite their known stabilizing effects, significant drawbacks exist to the use of protein excipients, such as albumin or gelatin, in a pharmaceutical composition. For example, albumin and gelatin are expensive and increasingly difficult to obtain. Furthermore, blood products or animal derived products such as albumin and gelatin, when administered to a patient can subject the patient to a potential risk of receiving blood borne pathogens or infectious agents. Thus, it is known that the possibility exists that the presence of an animal-derived protein excipient in a pharmaceutical composition can result in inadvertent incorporation of infectious elements into the pharmaceutical composition. For example, it has been reported that use of human serum albumin may transmit prions into a pharmaceutical composition. Thus, it is desirable to find suitable non-protein excipients, such as, e.g., stabilizers, cryo-protectants and lyoprotectants, which can be used to stabilize the protein active ingredient present in a pharmaceutical composition.
The unique characteristics of Clostridial toxins further constrain and hinder the selection of suitable non-protein excipients for a pharmaceutical composition comprising a Clostridial toxin. For example, Clostridial toxins are large proteins having an average molecular weight of approximately 150 kDa, and are further complexed with non-toxin associated proteins that increase the size to approximately 300-900-kDa. The size of a Clostridial toxin complex makes it much more fragile and labile than smaller, less complex proteins, thereby compounding the formulation and handling difficulties if Clostridial toxin stability is to be maintained. Hence, the use of non-protein excipients, such as, e.g., stabilizers, cryo-protectants and lyoprotectants must be able to interact with the Clostridial toxin in a manner which does not denature, fragment or otherwise inactivate the toxin or cause disassociation of the non-toxin associated proteins present in the toxin complex.
Another problem associated with a Clostridial toxin, is the exceptional safety, precision, and accuracy that is necessary for at all steps of the formulation process. Thus, a non-protein excipient should not itself be toxic or difficult to handle so as to not exacerbate the already extremely stringent requirements.
Still another difficulty linked with a Clostridial toxin, is the small amount of Clostridial toxin that is used in a pharmaceutical composition. As with enzymes generally, the biological activities of the Clostridial toxins are dependent, at least in part, upon their three-dimensional conformation. Thus, a Clostridial toxin is detoxified by heat, various chemicals, surface stretching, and surface drying. Additionally, it is known that dilution of a Clostridial toxin complex obtained by the known culturing, fermentation and purification methods to the much lower concentration used in a pharmaceutical composition results in rapid inactivation of the toxin. The low amount of a Clostridial toxin that is used in a pharmaceutical composition, makes this active ingredient very susceptible to adsorption to, e.g., the surfaces of laboratory glassware, vessels, to the vial in which the pharmaceutical composition is reconstituted and to the inside surface of a syringe used to inject the pharmaceutical composition. Such adsorption of a Clostridial toxin to surfaces can lead to a loss of active ingredient and to denaturation of the remaining Clostridial toxin, both of which reduce the total activity of the active ingredient present in the pharmaceutical composition. Hence, the use of non-protein excipients, such as, e.g., stabilizers, cryo-protectants and lyoprotectants must be able to act as surface blockers to prevent the adsorption of a Clostridial toxin to a surface.
Yet another problem connected to a Clostridial toxin, is the pH-sensitivity associated with complex formation. For example, the 900-kDa BoNT/A complex is known to be soluble in dilute aqueous solutions at pH 3.5-6.8. However, at a pH above about 7 the non-toxic associated proteins dissociate from the 150-kDa neurotoxin, resulting in a loss of toxicity, particularly as the pH rises above pH 8.0. See Edward J. Schantz et al., pp. 44-45, Preparation and characterization of botulinum toxin type A for human treatment, in Jankovic, J., et al., Therapy with Botulinum Toxin (Marcel Dekker, Inc., 1994). As the non-toxic associated proteins are believed to preserve or help stabilize the secondary and tertiary structures upon which toxicity depends, the dissociation of these proteins results in a more unstable Clostridial toxin. Thus, non-protein excipients useful to formulate a pharmaceutical composition comprising a Clostridial toxin must be able to operate within the confines of a pH level necessary to maintain the activity a Clostridial toxin.
What is needed therefore is a Clostridial toxin pharmaceutical composition wherein a Clostridial toxin active ingredient (such as a botulinum toxin) is stabilized by a non-protein excipient. The present compositions relate to solid and liquid Clostridial toxin active ingredient pharmaceutical compositions with one or more non-protein excipients which functions to stabilize the Clostridial toxin active ingredient present in the solid or liquid pharmaceutical composition.